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Reintroducing old `defined?' (was Re: Testing availabilty of a procedure)

Roland Orre <> writes:

> I think it is time to consider a redefinition of "defined?" to
> make it a special form.

Me too.  I was against changing `defined?' into a procedure from the
very start.  (Although I might have been a bit too lazy in my

I'd like to add the following argument:

* If `defined?' is a special form, it is easier for a compiler or a
  macro expander to expand conditionals testing for existence of a
  binding at compilation/macro expansion time.  `defined?' could, in
  this respect, be used for conditional compilation.

*** I suggest that we rename the current `defined?' into `bound?' and
    re-introduce scm's special form `defined?'.

In fact, I think this is such a good suggestion that I will do this
within a week from now, unless someone stops me.